The present invention relates to the process for passivating and stabilizing the surface of lead chalcogenides, and to the devices prepared thereby.
As used here, it is convenient to describe the surface of a semiconductor material that has been rendered inert to ambient gases as a passivate surface. It is well known that adsorption of oxygen onto the surfaces of lead chalcogenide crystals causes the formation of a strong p-type surface layer. For those not familiar with recent advances in this art, the following brief bibliography is offered:
Surface Interaction of H and O.sub.2 On Thin Epitaxic Films, by G. F. McLane and J. N. Zemel, Thin Solid Films, Vol. 7, pg. 229 (1971);
Photoconductivity In Lead Selenide, Experimental, by J. N. Humphrey and W. W. Scanlon, Physical Review, 105, 469 (1957);
Surface Transport Phenomena In PbSe Epitaxial Films, by M. H. Brodsky and J. N. Zemel, Physical Review, 155, 780 (1967);
The Effect Of Oxygen On Epitaxial PbTe, PbSe And PbS Films, by R. F. Egerton and C. Juhasz, Thin Solid Films, 4, 239 (1969). Although extensive work has been done with passivation of silicon aand germanium, (e.g., Oxidation Of Semiconductive Surfaces For Controlled Diffusion, U.S. Pat. No. 2,802,760, August, 1957 or Method Of Fabricating An Ensulated Gate Field-Effect Device, U.S. Pat. No. 4,010,290, March, 1977) little is known about passivation of the lead chalcogenides.